JP2004354399A - Ultrasonic probe system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cheaper sophisticated ultrasonic probe system which enables high-precision positional detection, using a small number of receiving elements. <P>SOLUTION: This ultrasonic probe system is provided with transmitting sections(CNT, TX, TD1, TD2) which contains transmitting elements(TD1, TD2) to transmit supersonic waves, a receiving section which has a plurality of receiving elements(TD1, TD2) receiving reflected waves from this transmitted supersonic wave object, to obtain two or more reception signals(a1, a2), azimuth detectors(M1, M2, LPF1, LPF2, ARG, DP) which detect azimuth of the object from phase differences among the azimuth functions, defined by shape/arrangement of the receiving elements and the reception signals(a1, a2) of these receiving elements, and an indicator sections(ADD, ABS, DP, DIS) which detect and display the position of the object, from both the detected azimuth and the signal propagation duration. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ultrasonic exploration apparatus, and more particularly to an ultrasonic exploration apparatus that can accurately detect the position of a school of fish.

  In order to search for the position of a school of fish, an ultrasonic search device called a fish finder has been used. A conventional fish finder emits ultrasonic waves into the water below the vessel on which it is mounted, receives reflected waves generated by objects such as schools of fish, and propagates the received reflected waves back and forth to the object. It is configured to calculate a distance from the time to the reflecting object.

  Conventionally, since a fish finder actually used has no azimuth resolution, a detected reflection object is processed as if it exists in an ultrasonic wave transmission direction such as immediately below a ship.

  To detect the direction of a reflecting object such as a school of fish, the principle of a phased array antenna used in the field of radio waves may be applied. That is, a plurality of ultrasonic receiving elements are arranged in the x direction, the y direction, or both the x and y directions, and the phase difference between the received reflected signals received by each ultrasonic receiving element is detected. What is necessary is just to detect the azimuth angle of the reflecting object that has generated.

  The configuration of such a phased array antenna employs an analysis method similar to geometric optics, in which the reflected wave is approximated by a single straight line assumed at the center of the beam. For this reason, when the size of the receiving element becomes too large to be ignored compared to the wavelength of the ultrasonic wave, there is a problem that a measurement error increases. This measurement error can be reduced to some extent by increasing the number of receiving elements and performing spatial averaging. However, if the number of receiving elements is increased in order to increase the measurement accuracy in this way, there is a problem that manufacturing costs increase.

  Accordingly, it is an object of the present invention to provide an inexpensive ultrasonic probe that can ensure high measurement accuracy with a small number of receiving elements. Another object of the present invention is to provide an ultrasonic search device that can easily grasp the three-dimensional position of a reflective object such as a school of fish from a display screen.

  An ultrasonic probe according to the present invention that solves the above-mentioned problems of the related art includes a transmitting unit that has a transmitting element and transmits ultrasonic waves, and a plurality of receiving elements that receive reflected waves of the transmitted ultrasonic waves from an object. A receiving unit that obtains a plurality of received signals, and an azimuth detecting unit that detects an azimuth of the object from an azimuth function determined by shapes and arrangements of the plurality of receiving elements and a phase difference between the received signals of the plurality of receiving elements. And a display unit for detecting and displaying the position of the object based on the detected direction and the required signal propagation time.

  Since the ultrasonic probe of the present invention is configured to detect the orientation of the reflecting object using the principle of physical optics, it is possible to detect the orientation with high measurement accuracy with a small number of receiving elements, and to reduce the cost. Therefore, an effect that a high-precision exploration device can be provided is achieved.

  According to a preferred embodiment of the present invention, the directivity of the transmitting element is set to be narrower than the directivity of each of the plurality of receiving elements. Are set to values larger than the respective apertures of the receiving elements. According to one preferred embodiment therefor, the transmitting element is constituted by connecting a plurality of receiving elements in parallel.

  According to still another preferred embodiment of the present invention, the azimuth detecting unit multiplies each of the received signals by a common reference signal when detecting a phase difference between the received signals of the plurality of receiving elements. It is configured to perform processing for generating a phase angle signal including the phase angle of the received signal by removing the high frequency component. Then, according to a preferred specific example for that, the direction detection unit calculates a complex conjugate product of the plurality of phase angle signals, and performs a process of detecting the argument as a phase difference between the plurality of reception signals. It is configured.

  According to still another preferred embodiment of the present invention, the display unit includes means for generating and displaying an A-mode signal by combining a plurality of reception signals or a plurality of phase angle signals. The plurality of receiving elements have a triangular, semicircular, or quarter circular shape. In addition, the plurality of receiving elements are configured by a quadrangle, which is sequentially given a double width, two receiving elements, and four receiving elements arranged in an orthogonal two-dimensional direction.

  According to still another preferred embodiment of the present invention, the ultrasonic search device is mounted on a ship, and the transmitting unit is configured to transmit ultrasonic waves into water substantially vertically below. The display unit displays an image in a plane orthogonal to the bow direction of the ship, or displays an image of the reflective object in a plane having a direction orthogonal to the bow direction of the ship and elapsed time in two dimensions. To display, or to display an image of a reflective object in each of a plane including the bow direction of this ship and a plane orthogonal to the bow direction, and further, a direction orthogonal to the bow direction of the ship and the bow direction It is configured to display an image of a reflecting object in a horizontal plane at a certain depth having two dimensions.

  According to a further preferred embodiment of the present invention, the display unit displays the images of the reflecting objects in the different planes simultaneously on the same display screen by dividing the same display screen or simultaneously on a plurality of adjacent display screens. It is configured as follows.

[Action]
Before describing the embodiment of the present invention, first, the basic principle of the azimuth measuring method based on the phase difference will be described with reference to FIG. As shown in (A), an ultrasonic wave is transmitted from the ultrasonic transmission element TT. The reflected signal generated by the object Q is
a ₀ (t) = 2A ₀ cos (ωt + φo)
= A ₀ [exp (j (ωt + φo)) + exp (-j (ωt + φo))] (1)
And

The incident signal aox (t) at the aperture position x is given by:
a ₀ x (t) = a ₀ (t + x sin θ / c)
= 2A ₀ cos (ωt + kx sinθ + φo)
= A ₀ [exp (j (ωt + kx sinθ + φo))
+ Exp (-j (ωt + kx sinθ + φo)))] (2)
k = 2π / λ, λ: wavelength of ultrasonic wave (3)
It becomes.

The ultrasonic receiving elements TD1 and TD2 receiving the incident signal a ₀ x (t) output the received signals a ₁ (t) and a ₂ (t), respectively. Here, assuming that the shape of the opening of the two receiving elements TD1 and TD2 is as shown in FIG. 3B, the projection w (x) of this opening shape on the x-axis is called the opening shape. If so, this is as shown in FIG. This opening shape w (x) is decomposed into w ₁ (x) and w ₂ (x) corresponding to the receiving elements TD1 and TD2, respectively, as shown in FIG.

When the aperture shape is defined as described above, the received signals a ₁ (t) and a ₂ (t) are given as follows.
a ₁ (t) = ∫w ₁ (x) · a ₀ x (t) dx
= A ₀ · exp (j (ωt + φ ₀ )) ∫w ₁ (x) · exp (jKx) dx
+ A ₀ · exp (-j (ωt + φ ₀ )) ∫w ₁ (x) · exp (-jKx) dx
＝ A ₀・ exp (j (ωt + φ ₀ )) W ₁ (K)
+ A ₀ · exp (-j (ωt + φ ₀ )) W ₁ ^* (k)
＝ A ₀・ exp (j (ωt + φ ₀ )) B ₁・ exp (jφ ₁ (k))
+ A ₀ · exp (-j (ωt + φ ₀ )) B ₁ · exp (-jφ ₁ (k))
= 2A ₀ B ₁ [exp (j (ωt + φ ₁ ) + exp (-j (ωt + φ ₁ )]]
= 2A ₀ B ₁ cos (ωt + φ ₁ ) (4)
φ ₁ = φ ₀ + φ ₁ (k) ・ ・ ・ (5)

a ₂ (t) = ∫w ₂ (x) · a ₀ x (t) dx
= A ₀ · exp (j (ωt + φ ₀ )) ∫w ₂ (x) · exp (jKx) dx
+ A ₀ · exp (-j (ωt + φ ₀ )) ∫w ₂ (x) · exp (-jKx) dx
＝ A ₀・ exp (j (ωt + φ ₀ )) W ₂ (K)
+ A ₀ · exp (-j (ωt + φ ₀ )) W ₂ ^* (K)
＝ A ₀・ exp (j (ωt + φ ₀ )) B ₂・ exp (jφ ₂ (k))
+ A ₀ · exp (-j (ωt + φ ₀ )) B ₂ · exp (-jφ ₂ (k))
= 2A ₀ B ₂ [exp (j (ωt + φ ₂ ) + exp (-j (ωt + φ ₂ )])
= 2A ₀ B ₂ · cos (ωt + φ ₂ ) (6)
φ ₂ = φ ₀ + φ ₂ (k) ・ ・ ・ (7)

Here, the symbol ∫ is an integral along the x axis from −infinity to + infinity. W ₁ (K) and W ₂ (K) are Fourier transforms of the shape coefficients w ₁ (x) and w ₂ (x), respectively, and W ₁ ^* (K) and W ₂ ^* (K) are W ₁ ^* (K), respectively. Is the complex conjugate of (K) and W ₂ (K). further,
K = k · sin θ ・ ・ ・ (8)
It is.

The phase difference Δφ between the two received signals a ₁ (t) and a ₂ (t) is a function of K (= k · sin θ), which is Θ (K). This phase difference Θ (K) is obtained for both the + ω component and the −ω component.
Δφ = Θ (K)
_{= Φ 2 (k) -φ 1} (k)
_{= Arg [W 2 (K)} ] - Arg [W 1 (K)] ··· (9)
It is. This phase difference Θ (K) as a function of K is called a phase difference function. This phase difference function Θ (K) is determined only by the aperture shape w.

The equation giving Δφ can be solved analytically or numerically for K, provided that this is within ± π,
K (= k sin θ) = Φ (Δφ) (10)
It can be expressed as.

  The function Φ (Δφ) gives the relationship between the phase difference Δφ of each received signal and the azimuth θ of the object that has generated the reflected wave to two receiving elements having an aperture of an arbitrary shape. This Φ (Δφ) is called an azimuth function. The azimuth function Φ (Δφ) can be obtained by calculating the values of Expressions (4) and (6) with an appropriate value set for θ.

Since the phase difference function Θ (K) is determined only by the shape w of the aperture, this azimuth function Φ (Δφ) is also determined only by the shape w of the aperture. Therefore, the azimuth function Φ (Δφ) is known. Therefore, based on the actually measured phase difference Δφ and the known azimuth function Φ (Δφ),
θ = sin ^-1 [Φ (Δφ) / K] (11)
Given as

An actual example of the phase function and the azimuth function as described above is shown for a case where the aperture shape is a rectangle shown in FIG. In the case of a rectangular opening, the shape coefficients w ₁ (x) and w ₂ (x) are as shown in FIG. Therefore, terms related to the phase angles φ ₁ (k) and φ ₂ (k) are
_{B 1 · exp (jφ 1 (} k))
= W ₁ (K)
= A ₀ · exp (j (ωt + φo)) ∫w ₁ (x) · exp (jKx) dx
= [1-exp (-jKμ)] / (jK)
= Exp (-jKμ / 2) [exp (jKμ / 2) -exp (-jKμ / 2)] / (jK)
= (2 / K) sin (Kμ / 2) ・ exp (-jKμ / 2) ・ ・ ・ (12)
It becomes. Therefore, the phase angle φ ₁ (k) is given by the following equation.
φ ₁ (k) =-Kμ / 2 ・ ・ ・ (13)

Similarly,
B ₂・ exp (jφ ₂ (k))
= W ₂ (K)
= A ₀ · exp (j (ωt + φ ₀ )) ∫w ₂ (x) · exp (jKx) dx
= [Exp (jKμ) -1] / (jK)
= Exp (jKμ / 2) [exp (jKμ / 2) -exp (-jKμ / 2)] / (jK)
= (2 / K) sin (Kμ / 2) ・ exp (jKμ / 2) ・ ・ ・ (14)
It becomes. Therefore, the phase angle φ ₁ (k) is given by the following equation.
φ ₂ (k) = Kμ / 2 ・ ・ ・ (15)

Therefore, the phase difference function Θ (K) in the case of FIG.
_{Δφ = φ 2 (k) -φ} 1 (k) = Θ (K) = Kμ = kμ sinθ ··· (16)
It becomes. From this relationship, the azimuth function Φ _R (Δφ) for a rectangular aperture is
Φ _R (Δφ) = K = k sin θ = Δφ / μ (17)
It becomes. Therefore, from this azimuth function, the azimuth θ of the object that caused the reflected wave is
θ = sin ^-1 [Φ (Δφ) / k]
= Sin ^-1 (Δφ / kμ) ・ ・ ・ (18)
Is calculated.

  FIG. 1 is a block diagram showing the configuration of an ultrasonic probe according to an embodiment of the present invention. CNT is a control unit, TX is a transmission unit, TD1 and TD2 are both transmitting and receiving elements (ultrasonic transducers), BL1 and BL1. BL2 is a transmission signal blocking section, AMP1 and AMP2 are amplification sections, M1 and M2 are carrier multiplication sections, CGN is a carrier generation section, LPF1 and LPF2 are low-pass filtering sections, ARG phase angle calculation sections, and ADD is a signal addition section. ABS is an absolute value calculation unit, DP is a digital processor, and DIS is a display unit.

  The transmitting unit TX outputs a transmission electric signal in accordance with a start command output from the control unit CNT. This transmitted electric signal is a burst-like signal created by amplitude-modulating a sine wave carrier (carrier) of a constant frequency in the ultrasonic band of several tens of kHz supplied from the carrier generation unit CGN with a pulse signal. is there. Hereinafter, such a signal is also referred to as a tone burst signal. The tone burst signal is supplied to the transmission / reception ultrasonic transducers TD1 and TD2, and simultaneously drives the transducers.

As shown in FIG. 5, each of the ultrasonic transducers TD1 and TD2 has the same rectangular opening shape with a diameter (width) μ and is arranged adjacent to each other. Simultaneously driving two adjacently located transducers of the same shape has the same effect as driving a single large diameter transducer with a diameter of 2μ. That is, an ultrasonic beam having a narrow beam width B _N is emitted from the large-diameter transducer.

  As illustrated in FIG. 5, a reflected wave is generated by a reflecting object Q such as a fish. This reflected wave is individually received by each of the ultrasonic transducers TD1 and TD2. The transmitting / receiving ultrasonic transducers TD1 and TD2 are used alone as small-diameter transducers in the case of the receiving operation. For this reason, each transducer operates so as to have a wide directivity Bw corresponding to a small diameter as compared with the case of a large diameter transmission operation.

The reflected wave received by each of the transducers TD1 and TD2 is converted into an electric signal in each, and then passes through the transmission signal blocking units BL1 and BL2 in FIG. 1 that selectively blocks only a large amplitude transmission signal. The signals are input to the amplifiers AMP1 and AMP2, and become amplified received signals a ₁ and a ₂ .

In this embodiment, as in the case illustrated in FIG. 4, since the shape of the ultrasonic transducer is the same, B1 = B2 holds in the above-described equations (4) and (6). If 2A ₀ B ₁ is A,
a ₁ (t) = A [exp (j (ωt + φ ₁ ) + exp (−j (ωt + φ ₁ ))] (19)
a ₂ (t) = A [exp (j (ωt + φ ₂ ) + exp (−j (ωt + φ ₂ ))] (20)

The received signals a ₁ (t) and a ₂ (t) output from the amplifiers APM1 and AMP2 are multiplied by the reference signals (carriers) supplied from the carrier generator CGN in the multipliers M1 and M2. This reference signal d is
d = exp (-jωt) (21)
And

The signals b1 and b2 output from the multipliers M1 and M2 are
b ₁ = a ₁ (t) × exp (-jωt)
= A _{[exp (jφ 1) + exp (} -j (2ω-φ 1)) ] (22)
b ₂ = a ₂ (t) × exp (-jωt)
= A _{[exp (jφ 2) + exp (} -j (2ω-φ 2)) ] ... (23)

The signals c ₁ and c ₂ obtained by passing the signals b ₁ and b ₂ given by the equations (22) and (23) through the low-pass filtering sections LPF1 and LPF2 are the _second signals of the equations (22) and (23). The higher order frequency 2ω of the term is removed. That is,
c ₁ = A exp (jφ ₁ ) (24)
c ₂ = A exp (jφ ₂ ) (25)
It becomes.

First, the phase angle calculation unit ARG calculates the complex conjugate product of the signals c ₁ and c ₂ output from the low-pass filtering units LPF 1 and LPF _{2 at} the preceding stage, and calculates the argument g. That is,
g = Arg [c ₁ c ₂ ^* ]
_{= Φ 1 (K) -φ 2} (K)
= Δφ
And the phase difference Δφ is obtained.

From the phase angle Δφ calculated by the phase angle calculation unit ARG and the azimuth function Φ _R (Δφ) = Δφ / μ of the rectangular aperture, the digital processor DP calculates the azimuth angle θ of the reflecting object into the equation (18). According to
θ = sin ^-1 (Δφ / kμ)
Is calculated.

On the other hand, in FIG. 1, the signals c ₁ and c ₂ output from the low-pass filtering sections LPF1 and LPF2 are added in an adding section ADD. The addition result h is
h = c ₁ + c ₂ = A [exp (jφ ₁ ) + exp (jφ ₂ )] (26)
It becomes.

From this addition result, the absolute value s is calculated in the next-stage absolute value calculating unit ABS. That is,
s = ABS [h]
= A · ABS [exp (jφ ₁ ) + exp (jφ ₂ )]
= 2A cos [(φ ₁ -φ _2)]
Is obtained.

Here, as in the case of the above-described wave transmitting operation, two ultrasonic transducers TD1 and TD2 are connected in parallel to form a single large-diameter receiving element, and a reflected wave is formed using this receiving element. Is assumed to be received. Assuming that the received signal in this case is u, this is given by the sum of the above-mentioned received signals a ₁ (t) and a ₂ (t).

That is,
u = a ₁ (t) + a ₂ (t)
= 2A cos (ωt + φ ₁ ) + 2A cos (ωt + φ ₂ )
= 4A cos [(φ ₁ -φ ₂₎ / _2] · cos _{[(2ωt + φ 1 + φ 2} ) / 2 ]
= 2s cos _{[(2ωt + φ 1 + φ 2} ) / 2 ]... (27)
Get the relationship.

  Equation (27) shows that s output from the absolute value calculating unit ABS is nothing but the envelope of the received signal u obtained when the large-diameter reception is performed by connecting the transducer pairs TD1 and TD2 in parallel. ing. Therefore, this absolute value s can be used as an A-mode signal.

  The digital processor DP calculates the distance R to the reflecting object from the time difference between the present time of the A-mode signal supplied from the absolute value calculating unit ABS and the transmission time notified from the control unit CNT. The digital processor DP creates a screen to be displayed on the display device DIS based on the azimuth θ of the reflecting object calculated from the phase angle g received from the phase angle calculating unit ARG and the calculated distance R to the reflecting object. Then, this is transferred to the display device.

  An example of a display screen displayed when the ultrasonic search device of the above embodiment is used for searching for a school of fish in the sea will be described with reference to FIG. The display screen (C) is an xy cross-sectional view in which the z-axis is set in the traveling direction of the ship on which the search device is mounted, and a portion including the search device is cut along a plane perpendicular to the z-axis. is there. The y-axis is set in the depth direction (vertically below) in the sea, and the x-axis is set in the side of the hull. This ship is assumed to be sailing at a constant speed in the z-axis direction. B1 in the sea is a single or a group of fish, and b4 is a seabed.

  The display screen (A) in FIG. 6 is a display screen similar to a general-purpose fish finder screen, in which the vertical axis indicates the depth in the sea (y-axis), and the horizontal axis indicates the elapsed time t. When the ship is traveling at a constant speed, the time axis t indicates the length (z-axis) measured in the traveling direction of the ship at the same time. In this case, the display screen (A) corresponds to a yz sectional view. In the display screen, a1, a2, and a3 are images (echoes) of reflected waves from a single or group of fish, and a4 is an echo of the sea floor.

  The display screen (C) in FIG. 6 is an xt (z) cross-sectional view at a specific depth y1 selected by the cursor. In this display screen, c1 and c3 are echoes of the fish present at the selected depth y1, and correspond to the echoes a1 and a3 in the display screen (A). Since the echo a2 exists at a depth different from the depth y1, it is not displayed on the display screen (C). Such three types of display screens (A), (B), and (C) as illustrated in FIG. 6 are simultaneously displayed in adjacent display areas, or one display screen is divided and simultaneously displayed. By doing so, it is possible to three-dimensionally grasp the positions of fish schools and fish bodies on the display screen.

  FIG. 2 is a block diagram showing a configuration of an ultrasonic probe according to another embodiment of the present invention. In this figure, the components denoted by the same reference numerals as those in FIG. 1 are the same as the components already described with reference to FIG. 1, and the overlapping description will be omitted.

  The ultrasonic probe of this embodiment is provided with four ultrasonic transducers TD1 to TD4 which operate as a transmitting / receiving element. In order to process reflected waves received by each of the transducers corresponding to these four transducers. , A transmission signal element unit BL, an amplification unit AMP, a multiplication unit M, and a low-pass filtering unit LPF. Further, the ultrasonic probe of this embodiment includes a selection unit SEL for selecting a transmission mode in accordance with a command received from the control unit CNT, an A / D conversion unit A / D, a digital processor DP, and a display unit CRT. .

  As shown in FIG. 7, the four ultrasonic transducers TD1 to TD4 are provided with a pair of TD1 and TD2 at a predetermined distance along the x-axis direction and at a predetermined distance along the z-axis direction. Then, a pair of TD3 and TD4 is arranged.

  Referring to FIG. 2 again, the selector SEL supplies the tone burst signal to only one of the four transducers to be driven in accordance with the transmission mode instructed by the controller CNT. The most frequently used transmission mode is to supply the same tone burst signal to the four ultrasonic transducers TD1 to TD4, combine the ultrasonic beams radiated from each of them to form an ultrasonic beam having a narrow width, Is a narrow beam transmission mode in which is emitted into the sea directly below.

  Ultrasonic waves radiated in the narrow beam transmission mode are reflected by a reflecting object such as a fish body in the sea, received by the ultrasonic transducers TD1 to TD4 as reflected waves, and converted into reflected signals of electric signals. The reflected signal of each receiving system is input to the A / D conversion unit A / D via the transmission signal blocking units BL1 to BL4, the amplification units AMP1 to AMP4, the multiplication units M1 to M4, and the low-pass filtering units LPF1 to LPF4. Here, after being converted into a digital signal, it is supplied to a digital processor DP and processed as a reflected signal of each receiving system.

  The digital processor DP calculates the azimuth of the direction in the xy section of the reflecting object from the phase difference between the respective reflected signals of the transducers TD1 and TD2, and calculates the reflecting object from the phase difference between the respective reflected signals of the transducers TD3 and TD4. Is calculated in the yz section. Also, a combined reflected signal is created by adding the reflected signals of the four transducers and used as the A signal. Further, the distance to the reflecting object is calculated based on how delayed the synthesized reflection signal appears from the transmission time of the tone burst signal. A three-dimensional position is detected from the azimuth and the distance of the reflecting object calculated in this way.

  FIG. 8 is a diagram for explaining a state of three-dimensional position detection performed using the ultrasonic search device of the embodiment described with reference to FIGS. 2 and 7. In this example, a screen display for detecting the position of the fish school in the three-dimensional space immediately below the hull is performed. In this example, three-dimensional display is possible even when the ship is stopped. FIG. 8A is a display screen showing the presence of a school of fish directly below the hull projected on the yz plane, wherein a1 and a2 are echoes of a school of fish and a single fish, and a3 is an echo of the sea floor. It is.

  FIG. 8B is a display screen showing the state of the school of fish immediately below the hull projected on the xy plane, and shows the presence of the school of fish in both directions (x-axis direction) of the hull. b1 and b2 are echoes of a school of fish or a single fish, and b3 is an echo of the sea floor. FIG. 8C is a display screen of a school of fish in the xz section at a specific depth y1 selected by the cursor. C1 in the display screen (C) is an echo of a school of fish existing at the selected depth y1. This echo appears as an echo a1 on the display screen (A) and as an echo b1 on the display screen (B).

  The echoes of the school of fish that appear as the echo a2 in the display screen (A) and as the echo b2 in the display screen (B) do not appear on the display screen (C) having different depths. In this way, by displaying three types of cross-sectional views adjacent to the same display device or dividing the same display screen and displaying the same at the same time, it is possible to detect the position of the fish school in the sea from the display screen. .

  As described above, an exploration device that detects the azimuth of a reflecting object from the phase difference between received reflected signals cannot determine the azimuth if the phase difference between reflected signals from objects such as fish schools exceeds ± π. become. In consideration of this point, as shown in FIG. 5, the width of the transmission beam is set so as not to be too large. Further, when the directivity of reception is set to be substantially the same as the directivity of transmission, the reception level sharply decreases in the peripheral portion of the beam, and the SN deteriorates. In order to avoid the deterioration of the SN, the directivity of reception is set to be larger than the directivity of transmission.

  In order to make the directivity of transmission wider than the directivity of reception, it is preferable that a transmitter / receiver transducer be installed, connected in parallel at the time of transmission and operated simultaneously, and operated individually at the time of reception. Some preferred examples of the shape and arrangement of such a dual-purpose transducer are shown in FIG. (A) and (B) show examples of division into a semicircular shape and a quarter circle shape, and (C) and (D) show examples of division into triangular shapes.

  Generally, as the width of the space occupied by the transmitting and receiving elements increases, the beam becomes sharper, and the field of view as a search device becomes narrower. Therefore, as illustrated in FIG. 10, by dividing the transducer into a plurality of portions so that the width of the transducer is successively doubled, the field of view can be changed over a wide range with a small number of elements.

  That is, in the case (A), the smallest transducers TD1 and TD2 are connected in parallel and transmitted at the same time, and TD1 and TD2 are used separately and received, so that a maximum field of view (smallest aperture) is obtained. Can work. Next, the three transducers TD1, TD2, and TD3 are connected in parallel to perform transmission, and TD1 and TD2 are connected in parallel, and TD3 is used individually for reception. (The second largest diameter).

  Lastly, the transmission is performed by connecting the four transducers TD1, TD2, TD3, and TD4 in parallel, and the reception is performed using the TD1, TD2, and TD3 connected in parallel and TD4 individually to perform reception. In the field of view (maximum aperture). The same applies to the case of FIG.

  As described above, the configuration in which the ultrasonic wave is radiated directly below the hull has been exemplified. However, the ultrasonic probe according to the present invention may also be applied to a case where ultrasonic waves are emitted at an appropriate angle shifted from the vertical direction and the direction of the reflecting object based on the emitted direction is detected.

  In addition, the present invention has been described by way of example in the case of exploring an object such as a school of fish in the sea mounted on a ship. However, the ultrasonic search device of the present invention can be used as a remote control monitoring device that is installed at an appropriate height on the ground and searches for a reflective object such as a suspicious person.

  According to an embodiment of the present invention, an image in a plane orthogonal to the bow direction of the ship is displayed, or the elapsed time and the direction orthogonal to the bow direction of the ship are in two planes. Display the image of the reflective object, display the image of the reflective object in a plane including the bow direction of this ship and in a plane orthogonal to the bow direction, and further, display the bow direction of the ship and the bow direction. Since it is configured to display the image of the reflecting object in a horizontal plane at a certain depth with the direction orthogonal to the direction as two dimensions, it is easy to determine the three-dimensional position of the reflecting object such as a school of fish from the display screen. The effect of being able to grasp is produced.

  Furthermore, according to a further preferred embodiment of the ultrasonic search device of the present invention, the display unit displays the image of the reflecting object in a different plane at the same time by dividing the same display screen, or a plurality of adjacent display screens. Since it is configured to be displayed simultaneously on the upper side, there is an advantage that the three-dimensional position of a reflecting object such as a school of fish can be easily and accurately grasped only from the display screen.

FIG. 2 is a functional block diagram illustrating a functional configuration of the ultrasonic search device according to one embodiment of the present invention. FIG. 11 is a functional block diagram illustrating a functional configuration of an ultrasonic search device according to another embodiment of the present invention. It is a conceptual diagram for explaining the principle of the present invention. FIG. 2 is a plan view showing an opening shape of a receiving element (ultrasonic transducer) of the ultrasonic probe of the embodiment in FIG. 1. FIG. 2 is a conceptual diagram illustrating the relationship between the directivity of transmission and the directivity of reception by an ultrasonic transducer for both transmission and reception of the ultrasonic probe of the embodiment in FIG. 1. FIG. 3 is an example of a display screen of the ultrasonic survey device of the embodiment shown in FIG. 1, a display screen (A) corresponding to a yz cross-sectional view, a display screen (B) corresponding to an xy cross-sectional view, and a specific screen. It consists of a display screen (C) corresponding to an xt (z) sectional view at the depth. FIG. 3 is a plan view showing the shape and arrangement of an element (ultrasonic transducer) for both transmission and reception of the ultrasonic probe of the embodiment shown in FIG. 2. FIG. 4 is an example of a display screen of the ultrasonic probe of the embodiment shown in FIG. 2, a display screen (A) corresponding to a yz sectional view, a display screen (B) corresponding to an xy sectional view, and a specific screen. It consists of a display screen (C) corresponding to an xt (z) sectional view at the depth. It is a top view which shows the example of the shape and arrangement | sequence of the ultrasonic transducer which can be used for the ultrasonic probe of the other Example of this invention. It is a top view which shows the example of the shape and arrangement | sequence of the ultrasonic transducer which can be used for the ultrasonic probe of the further another Example of this invention.

Explanation of reference numerals

CNT controller
TX transmitter
TD1-TD4 transmission / reception element (ultrasonic transducer)
BL1-BL4 transmission signal blocker
AMP1-AMP4 amplifier
M1-M4 Carrier multiplier
LPF1-LPF4 Low-pass filter
CNG carrier generator
ARG phase angle calculator
ADD signal adder
ABS absolute value calculator
DP digital processor
DIS display

Claims (17)

A transmission unit having a transmission element and transmitting an ultrasonic wave,
A receiving unit that has a plurality of receiving elements that receive reflected waves of the transmitted ultrasonic wave from the object, and obtains a plurality of received signals,
An azimuth detection unit that detects the azimuth of the object from an azimuth function determined by the shape and arrangement of the plurality of receiving elements and a phase difference between reception signals of the plurality of receiving elements,
A display unit for detecting and displaying the position of the object from the detected azimuth and the time required for signal propagation. In claim 1,
The directivity of the transmitting element is set narrower than the directivity of each of the plurality of receiving elements. In claim 2,
The ultrasonic probe according to claim 1, wherein the aperture of the transmitting element is set to a value larger than the aperture of each of the plurality of receiving elements. In claim 3,
An ultrasonic probe, wherein the transmitting element is configured by connecting the plurality of receiving elements in parallel. In claim 1,
The azimuth detecting unit, when detecting the phase difference between the received signals of the plurality of receiving elements, by multiplying each of the received signals by a common reference signal and then removing the high-frequency component to determine the phase angle of the received signal. An ultrasonic exploration apparatus that performs a process of generating a phase angle signal including the phase angle signal. In claim 5,
The ultrasonic detection apparatus according to claim 1, wherein the direction detection unit performs a process of calculating a complex conjugate product of the plurality of phase angle signals and detecting the argument as a phase difference between the plurality of received signals. In claim 1,
The ultrasonic search apparatus according to claim 1, wherein the display unit includes a unit that generates and displays an A-mode signal by combining the plurality of reception signals or the plurality of phase angle signals. In each of claims 1 to 7,
An ultrasonic probe, wherein the plurality of receiving elements have a triangular, semicircular, or quarter circular shape. In each of claims 1 to 7,
The ultrasonic exploration apparatus according to claim 2, wherein the plurality of receiving elements are formed in a quadrangular shape having a width twice as large. In each of claims 1 to 8,
The ultrasonic exploration apparatus according to claim 2, wherein the plurality of receiving elements include two receiving elements. In each of claims 1 to 8,
The ultrasonic exploration apparatus according to claim 2, wherein the plurality of receiving elements include four receiving elements arranged in an orthogonal two-dimensional direction. In each of claims 1 to 11,
An ultrasonic surveying device mounted on a ship, wherein the transmitting unit is configured to transmit the ultrasonic waves into water substantially vertically below. In claim 12,
The ultrasonic search device according to claim 1, wherein the display unit is configured to display an image in a plane orthogonal to a bow direction of the ship. In claim 12,
The ultrasonic search apparatus according to claim 1, wherein the display unit is configured to display an image of the reflecting object in a plane having a direction orthogonal to a bow direction of the ship and an elapsed time in two dimensions. In claim 12,
The ultrasonic search device, wherein the display unit is configured to display an image of the reflecting object on a plane including the bow direction of the ship and on a plane orthogonal to the bow direction. In claim 12,
The display unit is configured to display an image of a reflecting object in a horizontal plane at a constant depth having a bow direction of the ship and a direction orthogonal to the bow direction as two dimensions. Exploration equipment. In each of claims 13 to 16,
The ultrasonic search, wherein the display unit is configured to divide the same display screen into images of the reflecting object in the different planes and display them simultaneously or on a plurality of adjacent display screens at the same time. apparatus.

Images